Projectile



Aug. 22, 1961 C. L. CRITCHFIELD ETAL PROJECTILE Filed Sept. 26, 1944 F/GJ FIG. 3

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|NvENToRs CHARLES L. CR/TCHF/ELD BY JOHN Mc. M/LLAR AT NEY United States Patent 2,996,992 PRQJECTILE Charles L. Critcheld, `Chevy Chase, Md., and John McG. Millar, Utica, N.Y., assignors to the United States of America as represented by the Secretary of the Navy Filed Sept. 26, i194:4, Ser. No. '555,856 2 Claims. (Cl. 1102-93) The present invention relates generally to projectiles and more particularly to a sabot type `of projectile as disclosed in the co-pending application of lohn McG. Millar, Serial No. 541,923, led June 24, 1944, being of nove] construction and having means for positively retaining the component elements of the projectile in assembled relation until red from a gun.

Sabot projectiles generally include a sleeve of cylmdrical form closed at one end and adapted to receive a projectile core of a caliber substantially less than that of the sabot. When the assembled sabot and projectile are -red from a gun, it is desired that the sabot be immediately discarded after leaving the muzzle of the gun, to reduce Aair resistance. At the point of exit from the gun bore, the functions of the sabot will have been attained, namely, to provide a pressure area for the projectile equal in area to that of a full caliber projectile to imporat rotation to the subcaliber projectile, and to provide a centering means for the subcaliber projectile. Due to centrifugal force generated at the time of tiring, the sabot will be expanded to a sliding fit with the subcaliber projectile. Upon entrance into the atmosphere from the gun bore, air resistance is encountered, the drag of which is sufficiently great to retard and slide the sabot rearwardly from the projectile, allowing the projectile to proceed to its target unrestricted.

Where a sliding iit is used between the sabot and projectile for discarding thereof, a releasable retaining means must be employed to prevent displacement of the component elements prior to ring. In packing such projectiles and in loading them into guns, one or more of the component elements of the projectiles may fall off in absence of suitable retaining means.

One of the principal objects of this invention is to provide a sabot projectile in which the components are held together securely by retaining means which release positively in response to centrifugal force.

Another object of the invention is to provide `a sabot projectile having a centrifugally releasable retaining means comprising a split ring engaging an annular groove of the projectile and a wall of the sabot for retaining the component elements as a unit.

A further object 4of the invention is to provide a sabot projectile having retainingmeans, subject to centrifugal force for freeing thereof, employing a series of detent elements adapted to occupy radially directed bores in the projectile, the detents engaging the sabot and being conned within the bores by a thin ring secured to the detent elements, as by soldering, the ring being breakable under centrifugal force.

These and other objects will become more apparent as the detailed description of the invention proceeds.

In the drawings:

FIG. l is a longitudinal sectional view of one form of the invention, taken along line 1-1 of FIG. 2;

FIG. 2 is an elevational View partly in section of the rear end of the projectile, showing the retaining means therefor;

FIG. 3 is a longitudinal sectional view of a modied form of the invention;

FIG. 4 is an elevational view of the rear end of the modified embodiment shown in FIG. 3;

FIG. 5 is an elevational view partly in section of still another modication of the invention;

2 FIG. 6 is a transverse View taken on .line 6 6 of FIG. 5, and

FIG. 7 is an enlarged perspective View of the centrifugally releasable retaining means shown in FIGS. 5 and 6. In the drawings like numerals designate identical parts throughout the various views, except in the modified embodiments wherein like parts are distinguished by the' exponent letters a and b.

Referring to the drawings, and more particularly to the FIGS. l and 2, numeral 10 indicates generally a bourrelet for a projectile, the bourrelet comprising a sleeve 11 of reinforced plastic or light weight alloy, and a base plug or sabot 12 of metal. The sleeve 11 has an enlarged axial bore 13 communicating with a coaxial reduced bore 14 in the sabot 12. A hollow boss 15 of the sabot tits into the rear end of the sleeve 11, where the parts may be held together by a press fit. Externally of the sabot a turning band 16 is secured, as by shrinking or other conventional method. The rear end ofthe sabot 12 has a conical recess 17 which communicates at its front or reduced end with the reduced bore 14.

Snugly iitted in the bourrelet is a subcaliber projectile core 18, the forward end of which terminates in an ogive portion 19, the rear end of the core having a reduced shank 20 normally occupying the reduced bore 14. Short of the end of the shank 20, an annular groove 21 is provided and is adapted to accommodate a split ring 22 made preferably of spring steel, and hence resilient. It will be observed that axial movement or displacement of the sabot 12 and projectile core 18 is prevented by the retaining means 22. More specifically, axial displacement between the sabot and projectile core is prevented prior to tiring by the expansible ring 22 seated in the annular groove of the projectile and engaging the conical wall of the base plug.

When the sabot projectile is red from a gun, the rifling in the gun barrel cuts into the turning band 16 o-f the base plug 12, producing a spinning of the sabot. It should be noted that the spinning of the sabot is transmitted to the projectile core in two ways. First, the snug tit between the sleeve 11 and the projectile core will create considerable frictional drag up to a certain point when the sleeve will be expanded under centrifugal force to a sliding yfit with the projectile core. Secondly, the frictional engagement of the transverse walls of the sleeve 11 and base plug at the shoulder 23 left by formation of the shank 2li provides a medium of torque transmission. When the tiring occurs, the force of the explosion will press the surface 25 of the base plug against the surface 26 of the inertially retarded projectile core, producing a frictional engagement sufficient to rotate the projectile core.

When the maximum rate of spin has been attained, which is shortly after the projectile has cleared the gun, centrifugal force will have expanded the split ring 22 to the point where it clears the annular groove of the shank 19. Also, the sleeve 11 which is of expandable material will have been expanded an amount suliicient to allow forward air pressure to slide the sabot land retaining means from the projectile core. The projectile core is then free to proceed alone to its target.

The embodiment shown in FIGS. 3 and 4 comprises a sleeve 11a which encircles the projectile core 18a. At its front end portion, the projectile core has an enlarged bulbous head 27 disposed in a recess 28 in the sleeve 11a, thus preventing displacement of the sabot in a forwardly direction. The rear end of the sleeve 11a abuts a wall 29 of the base plug 12a. A shank 20a is screwed into the rear end of projectile core 18a and protrudes through a co-axially positioned bore 14a of the base plug. As in the previously described form, an annular groove 21a in the shank receives a split ring 22a which retains com.-

ponent elements in their proper relative positions until acted upon by centrifugal force.

In the form shown in FIGS. 5, 6 and 7, a shank 20b has near its rear end a ser-ies of radially directed bores 30 adapted to receive detents v31. A line wire ring 32 is fastened to the detents, ras by solder spots 33, and positively retains the detents 31 within the bores 30 prior to tiring. When firing occurs, centrifugal force snaps the wire 32, thereby freeing detents 31 which are released from the shank so as to -allow the sabot to `slide off the rear end of the projectile core under air pressure incident to the flight of the projectile.

It will be observed that the new projectile is simple and compact in form and that its relatively few parts are held securely in assembled relation by retaining means which operate positively under centrifugal force to release the sabot parts lfrom the core. The conical wall at the rear end of the base plug contributes to holding the retaining means in position until acted upon by centrifugal force.

We claim:

1. A rotary sabot projectile comprising a subcaliber core having a reduced shank at its rear end, a substantially full caliber sabot 'having an axial bore through which the shank extends, the shank being itted closely in the bore and having a recess to the rear of the sabot, and a resilient ring seated in said recess and engaging the r4V rear end of the sabot for locking the sabot against the core, the ring being expansible out of said recess because of its resilience under centrifugal force to release the sabot from the core.

2. A rotary sabot projectile comprising a subcaliber core having a reduced shank forming a shoulder at its rear end, a substantially full caliber sabot having an axial bore through which the shank extends, the shank being tted closely in the bore and having a peripherall groove, the rear end of the sabot having a conical `opening communicating at its reduced end With'said bore and receiving the grooved portion of the shank, and an expansible ring seated in said groove and engaging the reduced end of the conical Wall of said opening for locking the sabot against the core shoulder, the ring being expansible out of said recess under centrifugal force to release the sabot from the core.

References Cited in the le of this patent UNITED STATES PATENTS 217,756 Varney July 22, 1879 388,413 Hawley et al. Aug. 28, 1888 1,209,611 Mustin Dec. 19, 1916 FOREIGN PATENTS 1,430 Great Britain June 17, 1856 131.034 Great Britain Aug. 21, 1919 s, am. 

